As a light device of a vehicle, various light devices such as a head lamp, a brake lamp, a turn signal lamp, and a tail lamp are provided. The existing light device has mostly used an incandescent lamp. Recently, the incandescent lamp tends to be replaced by a light emitting diode (LED).
FIG. 1 is a diagram illustrating the existing light device installed at a rear of a vehicle using a light emitting diode.
Referring to FIG. 1, the existing light device uses a plurality of light emitting diodes installed in a direct type to perform lighting. To this end, a printed circuit board is installed to correspond to a region to which light will be emitted and a plurality of light emitting diodes are mounted on the printed circuit board at a predetermined interval. Accordingly, when the light device emits light, the plurality of light emitting diodes are configured to emit light.
As described above, the light device in which the plurality of light emitting diodes are installed in the direct type may not perform surface emission, and therefore when an area to which light will be emitted is wide, the number of light emitting diodes to be mounted needs to be increased as much as the widened area. In addition, as described above, when the light emitting diode is installed in the direct type, a spot phenomenon may occur at a position where the light emitting diode is installed.
FIG. 2 is a diagram illustrating the existing another light device installed at a rear of a vehicle using a light emitting diode.
As described, to improve the direct type light device illustrated in FIG. 1, as illustrated in FIG. 2, light emitted from the light emitting diode is diffused to the light guide plate in a state in which the light emitting diode is installed at one side of the light guide plate to perform the surface emission. Japanese Patent Laid-Open Publication No. 2014-149995 (Vehicular Lamp, Published on Aug. 21, 2014, hereinafter, referred to as Cited Document) discloses the above-mentioned configurations.
However, if a light emitting diode module is installed at one side of the light guide plate as disclosed in the cited document, even if the vehicular lamp is configured to enable the light emitted from the light emitting diode to perform the surface emission in the light guide plate, as the light is getting farther away from the light emitting diode, light intensity is weak, such that the surface emission efficiency may be suddenly reduced at a position remote from a position at which the light emitting diode is installed.
That is, all of the light emitted from the light emitting diode installed at one side of the light guide plate does not reach the other side which is an opposite side of the light guide plate, such that the surface emission efficiency may be reduced at the other side of the light guide plate.